/* Copyright (c) 2001-2004, The HSQL Development Group
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 *
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 *
 * Neither the name of the HSQL Development Group nor the names of its
 * contributors may be used to endorse or promote products derived from this
 * software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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package com.hengpeng.common.util;

import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

// boucherb@users 20030705 - patch 1.7.2 - renamed methods to allow
// sp/sf calls
// under HSQLDB's current inability to resolve method name overloads.

/**
 * Provides a static utility interface to an MD5 digest algorithm obtained through the java.security.MessageDigest spi.
 * * Database end-users may wish to access the services of this class * to provide, for instance, application user
 * lookup tables with * one-way password encryption. For example: * -- DDL CREATE TABLE USERS(UID INTEGER IDENTITY,
 * UNAME VARCHAR, UPASS VARCHAR, UNIQUE(UNAME)) CREATE ALIAS MD5 FOR "org.hsqldb.lib.MD5.encodeString" -- DML & DQL
 * INSERT INTO USERS(UNAME, UPASS) VALUES('joe', MD5('passwd')) UPDATE USERS SET UPASS = MD5('newpasswd') WHERE UNAME =
 * 'joe' AND UPASS = MD5('oldpasswd') SELECT UID FROM USERS WHERE UNAME = 'joe' AND UPASS = MD5('logonpasswd') NOTE: *
 * Although it is possible that a particular JVM / application installation may * encounter NoSuchAlgorithmException
 * when attempting to get a jce MD5 message * digest generator, the likelyhood is very small for almost all JDK/JRE 1.1
 * * and later JVM implementations, as the Sun java.security package has come, * by default, with a jce MD5 message
 * digest generator since JDK 1.1 was * released. The HSLQLDB project could have provided an MD5 implementation to *
 * guarantee presence, but this class is much more lightweight and still allows * clients to install / use custom
 * implementations through the * java.security.MessageDigest spi, for instance if there is no service * provided by
 * default under the target JVM of choice or if a client has * developed / provides, say, a faster MD5 message digest
 * implementation. * In short, this class is a convenience that allows HSQLDB SQL Function and * Stored Procedure style
 * access to any underlying MD5 message digest algorithm * obtained via the java.security.MessageDigest spi * *
 * @author boucherb@users.sourceforge.net *
 * @version 1.7.2 *
 * @since 1.7.2
 */
public final class MD5
{
	/** * The jce MD5 message digest generator. */
	private static MessageDigest md5;

	/**
	 * * Retrieves a hexidecimal character sequence representing the MD5 * digest of the specified character sequence,
	 * using the specified * encoding to first convert the character sequence into a byte sequence. * If the specified
	 * encoding is null, then ISO-8859-1 is assumed * *
	 * @param string the string to encode. *
	 * @param encoding the encoding used to convert the string into the * byte sequence to submit for MD5 digest *
	 * @return a hexidecimal character sequence representing the MD5 * digest of the specified string *
	 * @throws HsqlUnsupportedOperationException if an MD5 digest * algorithm is not available through the *
	 *         java.security.MessageDigest spi or the requested * encoding is not available
	 */
	public static final String encodeString(String string, String encoding) throws RuntimeException
	{
		return StringConverter.byteToHex(digestString(string, encoding));
	}

	/**
	 * * Retrieves a hexidecimal character sequence representing the MD5 * digest of the specified character sequence,
	 * using the specified * encoding to first convert the character sequence into a byte sequence. * If the specified
	 * encoding is null, then ISO-8859-1 is assumed * *
	 * @param string the string to encode. *
	 * @param encoding the encoding used to convert the string into the * byte sequence to submit for MD5 digest *
	 * @return a hexidecimal character sequence representing the MD5 * digest of the specified string *
	 * @throws HsqlUnsupportedOperationException if an MD5 digest * algorithm is not available through the *
	 *         java.security.MessageDigest spi or the requested * encoding is not available
	 */
	public static final String encodeString16Bit(String string, String encoding) throws RuntimeException
	{
		return StringConverter.byteToHex(digestString(string, encoding)).substring(8, 24);
	}

	/**
	 * * Retrieves a byte sequence representing the MD5 digest of the * specified character sequence, using the
	 * specified encoding to * first convert the character sequence into a byte sequence. * If the specified encoding is
	 * null, then ISO-8859-1 is * assumed. * *
	 * @param string the string to digest. *
	 * @param encoding the character encoding. *
	 * @return the digest as an array of 16 bytes. *
	 * @throws HsqlUnsupportedOperationException if an MD5 digest * algorithm is not available through the *
	 *         java.security.MessageDigest spi or the requested * encoding is not available
	 */
	public static byte[] digestString(String string, String encoding) throws RuntimeException
	{
		byte[] data;
		if (encoding == null)
		{
			encoding = "ISO-8859-1";
		}
		try
		{
			data = string.getBytes(encoding);
		}
		catch (UnsupportedEncodingException x)
		{
			throw new RuntimeException(x.toString());
		}
		return digestBytes(data);
	}

	/**
	 * * Retrieves a byte sequence representing the MD5 digest of the * specified byte sequence. * *
	 * @param data the data to digest. *
	 * @return the MD5 digest as an array of 16 bytes. *
	 * @throws HsqlUnsupportedOperationException if an MD5 digest * algorithm is not available through the *
	 *         java.security.MessageDigest spi
	 */
	public static final byte[] digestBytes(byte[] data) throws RuntimeException
	{
		synchronized (MD5.class)
		{
			if (md5 == null)
			{
				try
				{
					md5 = MessageDigest.getInstance("MD5");
				}
				catch (NoSuchAlgorithmException e)
				{
					throw new RuntimeException(e.toString());
				}
			}
			return md5.digest(data);
		}
	}
}
